The authors describe changes in heart rhythm that appeared during ergometric testing in the Orasje General Hospital. During 1999-2000 a total od 239 ergometries were performed. 122 on males, and 117 on females. There were 41 case positive, and 158 negative. 10 testings were stopped due to hypertensive reactions, 21 were borderline cases and 9 were with inadequate ergometric level. At rest 2 cases of SVE appeared, and 7 cases with VES, 4 cases of preexitation 2 cases of complete LBBB, 1 case with incomplete LBBB, 4 cases with complete RBBB, and 11 cases with incomplete RBBB, and 1 case of sinus bradycardia. During testing, 55 cases developed SVE, and 57 developed VES, Prexitation appeared in 8 cases. The branch blocks persisted during testing except in one case whwn it dissapeared. Atrial fibrilation appeared in one patient. Although expirience says that chestpain appears in 50% of the tested patients during ergometric testing with significant changes in the ST segment, the appearance of rhythm abnormalities together with changes in the ST segment (elevation or depression) is a valuable diagnostic sign for diagnosting or predicting probable myocardial infarction or probable sudden cardiac death. As we evaluate all results during erometric testing together with the whole clinical satus of the patient we also have to evaluate the pathological changes of heart rhythm during testing and should never underestimate the value of it.